In cargo areas of airports, goods are handled in so-called ULDs, which is the term used to refer to the standard transporting containers, these advantageously being adapted three-dimensionally to the profile of the fuselage. The goods are usually delivered on the land side, via entry gates, at which trucks or railroad cars dock. The goods are then transported in the ULDs, via bypass conveyors (conveying paths), to the other side of the cargo area, where they are kept on standby on the air side, in the vicinity of the apron of the airport. The same likewise applies in reverse, when ULDs are flown in with freight and have to be distributed to the appropriate trucks or railroad cars in order to be transported further. In conventional airport cargo areas, it is not possible, as a result of the usually simple design of the bypass conveyor, for the transporting paths to be used simultaneously for transporting the ULDs in both directions.
Although the goods are often delivered in correspondence with their loading times (just in time), it is often not possible to synchronize delivery and further transportation. Examples of reasons for this are that the aircraft is late or the supply conveyors are already occupied by other assembled orders. In such a case, most of the ULDs, prior to being loaded into the vehicle or aircraft, have to be introduced into a ULD store, where they are buffer-stored. In reality, it is therefore the case that even ULDs which are definitely going to be needed very shortly nevertheless have to be introduced into the main ULD store, with high outlay, with the aid of elevating transfer vehicles (ETVs) or monorail equipment. This operation is imperative in order for the transporting paths, on which buffer storage, but no sorting, is possible, to be kept free for subsequent consignments of cargo.